This invention relates generally to lathe machines and more particularly concerns the swarf accumulated during the lathe shaping of certain metals and plastics.
In the lathe shaping of wood and also of plastics based in thermoset resins, the resulting swarf generally consists of fine particles or powder. Swarf in this form is readily collected by vacuum into a relatively high density mass suitable for storage and transport. However, in the lathe shaping of metals and of plastics based in thermoplastic resins, the swarf is accumulated in long, continuous, curled or spiraled strands.
For example, one such plastic is the shock resistant, virtually indestructible polycarbonate used in safety lenses, children's spectacle lenses and the like. In the lathe shaping of such lenses, the resulting polycarbonate strand makes swarf removal difficult because it easily tangles and snags, interrupting flow of the swarf along the vacuum path and backing the swarf up into the lens generating equipment. It also adversely affects the surface finish of the lens as the swarf collects around the cutting tool. Similar problems are experienced in other lathe applications.
In the spectacle lens industry, present solutions to the swarf strand problem include chipping, melting and constant vigilance approaches. In the chipping approach auxiliary equipment in the vacuum path breaks or mulches the swarf strand into small segments that are more easily manageable. Such equipment is costly, extremely noisy and readily subject to failure as broken swarf frequently finds its way into the equipment's bearings. The melting approach, while technically feasible, is unfortunately impractical as further auxiliary equipment is required to collect the swarf and bring the swarf to melting temperatures. The resulting solidified mass presents a new set of management problems all its own. The constant vigilance approach requires the continuing presence of supervisory personnel to interrupt operation of the lathe, remove the swarf and restart the lathing process every time tangling, snagging or undesirable collection of swarf occurs. The result is frequent and lengthy down time. Even after the lathe is cleared of this swarf, the swarf still remains in its unmanageable long strand condition.
It is, therefore, an object of this invention to provide a swarf control which causes swarf produced by a lathe to be segregated into manageable lengths. A further object of this invention is to provide a swarf control which causes swarf to be segmented by the lathe itself rather than by auxiliary equipment not otherwise needed in the lathing process.